Recently, fuel cells attract particular attention because electric energy can be directly obtained by an electrochemical reaction of a fuel, and it is advantageous that they have high generating efficiency with little emission of harmful materials, and facilitate the reduction of weight and size.
Meanwhile, hydrogen gas or methanol has been used as a fuel for fuel cells, and it is necessary to take care in handling these fuels. Hydrogen gas is one of flammable gases that can ignite upon reaction with oxygen in the air, if an ignition source having a certain temperature or more is present when the concentration of hydrogen in the air is 4% to 75%. Therefore, there is a possibility of ignition, if hydrogen gas is mixed with the air in a fuel cell as a result of, for example, generation of cracks in a separator plate or fracture in an electrolyte film; and thus extra safety and careful handling are required. Methanol is also a volatile and flammable material and it can have an adverse influence on the human body when inhaled in the human body. Moreover, it is known that methanol produces an oxidation reaction intermediate, such as formic acid or formaldehyde, which can also adversely affect the human body. Therefore, there has been a demand for a development of a fuel cell system provided with a fail-safe mechanism.
To cope with this demand, methods have been recently proposed which store a fuel in a form of a gel. However, although these disclosures use a fuel in a form of a gel, they do not contemplate efficiently extracting the fuel therefrom. That is, for example, some of the fuel cannot be extracted from the inside of the gel when generating electricity, bringing about considerable fuel loss and low generating efficiency in these methods.
Other and further features and advantages of the invention will appear more fully from the following description, taken in connection with the accompanying drawings.